Magnetic-core inductance device



Aug. 31, 1948. A. P. OLESKY MAGNETIC-CORE INDUCTANCE DEVICE Filed July 2, 1945 INVENTOR. ANTHONY P OLESKY ATTORNEYS Patented Aug. 31, 1948 v UNITED. ,sTArr-zs PATENT 'oFFlcs 2.44am I Anthony P. Oleshy, Chicago, 111., assignor to Belmont Radio Corporation, a corporation of Illinois Application July z, 1945. serial a. scam 2 china. 111-442) 1 -'I'his' invention relates to magnetic-core inductance devices and, while it is of general application, it is particularly suitable for embodiment in radio-frequency and intermediatefrequency transformer having magnetic cores individually associated with the primary and secondary windings-thereof and individually adjustable to adjust the primary and secondary self-inductance values. 7

There .are widely used in radio-broadcast receivers intermediate-frequency; transformers having magnetic cores individually associated with the primary and secondary windings which are generally compohents'oi an intermediatefrequency selector including fixed condensers connected in parallel with the primary and secondary windings.

justed to compensate for differences in the inherent inductance and capacitance of the connected circuit to tune the intermediate-fre quency selector accurately to the intermediatefrequency of the receiver. The present invention .is especially adapted for embodiment in such devices.

It is an object of the invention, therefore, to i has rea'dily reproducible performance characteristics.

In accordance with the invention, an inductance device comprises a tubular form of insulation material having a positioning aperture The inductance values of the primary and secondary windings are adtherein and an inductance winding disposed on 'the form. A core of magnetic material is dis- -reference is had to the following description taken in connection with the accompanying drawings while itsscopewill be pointed out in the appended claims.

Referring now to the drawings, mg, l is a longitudinal sectional view of an intermediatefroquency transformer embodying the invention;

while Fig. 2 is a detailed perspective view of the annular expansible member for positioninl and supporting a magnetic core forming a com-p ponent of thedevice.

Referring now to the drawings, there is illustrated an adjustable magnetic-core. inductance device embodying. the invention and comprising a tubular form" II of insulation material having small, circular positioning apertures Ila and -:Ilb therein. Disposed on the form II" and in spaced relation to each other are a pair of inductance windings Ho and Ill; spaced well away from and betweenthe positioning. apertures Ilia, Illb. Disposed'within the form ll are a pairof cores Ila'and llb of magnetic material which may .be in the form of molded plugs of powdered iron-in a cementing binder. The cores ila. and ilb are disposed to be coupled with the windings Hg and Ilb, respectively, and are pro--' vided'withs'upporting portions, for example with threaded supporting stems Ila and Ill), respectively.

The inductance device also includes a pair ofannular resilient expansible members a, llb disposed within and snugly fitting the form I. and provided with projecting portions engaging the positioning apertures Ila, Ilb, respectively, and also including portions engaging. and adiustably supporting the cores Ila, Ilb, respectively, to position the same. Each of the members Ila, Ilb may be in the form of the member Ila shown in detail in Fig. 2, consisting of an integral stamping of resilient sheet metal, such l as Phosphor bronze, stamped into the form of a split sleeve and having a projecting lug or ear Ilc adaptedto engage an aperture in the form I I. From the opposite ends of 'the sleeve Ila. and diametrically opposite to the split thereof are a pairof axially extending strips lid and lie from which extend a pair of circular collars I4! and Ilg, respectively. The strips lid and Ile comprise means for resiliently supporting the collars Ill and Ilg, respectively, from the sleeve Ila and the tinit is so formed that the'collars II) and Hg normally extend at relatively small opposed angles to the normal to the axis of the sleeve Ila and therefore to the axis of the tube ll when mounted therein. These flared collars Ill and Ila are proportioned to en-' age one of the threaded stems Ila and Ilb of" the magnetic cores Ila and Ilb, respectively, to grip the stem firmly and to position the respective' one of' the cores Ila and Ilb accurately within the form II and and therefore with .iespect to the windings Ila or Ilb.

I 3 The form II of insulation material may be supported at one end from a suitable base II of insulation material, such as "Bakelite." by means of a pair of concentric resilient ferrules II and I1 engaging the inner and outer surfaces 01' r the form l and cooperating to form an eyelet to secure the form ill to the base l5. If desired, the inductance: device described may be enclosed within a conventional shield can I! provided with extending lugs lBa for securing the device as a unit to a broadcast receiver chassis in a conventional manner.

In assembly of the inductance device of the invention, the sleeves Ila and Nb consisting of integral sheet metal stalznpings, as described, are

first threaded upon 'the supportingstems lla, lib of the magnetic cores l2a, lib, respectively. The sleeves are then slightly compressed and slid into opposed ends of the form lll until the projecting lugs llc of the sleeves Ila, llb engage the positioning apertures Ma, llb, of the form lll, whereupon the cores Ila, lib are positioned approximately correctly with respect to their respective windings Ha, llb. The threaded supporting stems l3a, lib of the magnetic cores l2a, l2b, respectively, may be adjusted by means of the screw-driver slots provided therein to adjust individually the self-inductance values of the windings Ila and 1 lb. When the device is connected into an intermediate-frequency selector circuit, the inductances of the windings i la, l lb maybe adjusted in a conventional manner to tune the selector .tothe mean intermediateJ-requency of the receiver, 'that is to align the intermediate-frequency selector, compensating for variations in the inherent inductance and capacitance of the circuits connected to the primary and secondary windings. The cores I24 and P2!) are shown in their mean rposistions in solid lines while their positions of maximum induct-ance are shown in dotted lines and their positions of minimum inductance in dashed lines.

Thus there is provided by the invention an improved, adjustable magnetic-core inductance destem.

4 assembly and yet one which at the same time provides a. high degree of accuracy and a readily reproducible performance characteristic.

While there has been described what is at 'present considered to be the preferred embodiment of the invention. it willbe apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit or scope of the invention.

What is claimed as new is:

1. An inductance device comprising a tubular form of insulation material having a positionlng aperture therein, an inductance winding disposed on said form and spaced from said aperture, a core of magnetic material adapted to be positioned within said form and having a supporting stem thereon, and a resilient member including a portion adapted to receive said supporting stem of said core and a projecting portion, said member being adapted to be compressed and slid in said form while in assembled relation with said core to a position in which said projection on said member engages said positioning aperture in said form to approximately position said core with respect to said winding,

said supporting stem of said core being adjust-- ANTHONY P. OLESKY.

REFERENCES CITED,

The following references are of record in the iiie of this patent:

UNITED STATES PATENTS Number Name Date 2,165,575 Polydonoff July 11, 1939 2,258,652 James Oct. 14, 194i Zepp Nov. 23, 1943 

